The present invention relates to a one-piece solid golf ball characterized by good rebound resilience and flying performance.
Many attempts have so far been made to impart good rebound resilience to golf balls by improving the compounding of polybutadiene as a rubber base material.
For example, JP-A 62-89750 discloses a rubber composition for solid golf balls which is compounded from a polybutadiene having a Mooney viscosity of 70 to 100 synthesized with a catalyst of Ni and Co and either of a polybutadiene having a Mooney viscosity of 30 to 90 synthesized with a catalyst of lanthanoid or a polybutadiene having a Mooney viscosity of 20 to 50 synthesized with a catalyst of Ni and Co. The rubber composition, however, has room for further improvement in rebound resilience.
JP-A 2-268778 discloses a golf ball formed from a rubber composition compounded from a polybutadiene having a Mooney viscosity lower than 50 which is synthesized with a catalyst of Group VIII element and a polybutadiene having a Mooney viscosity lower than 50 which is synthesized with a catalyst of lanthanoid. This golf ball, however, is poor in rebound resilience.
Moreover, JP-A 11-70187 discloses a multi-piece solid golf ball having an intermediate layer formed from a polybutadiene having a low Mooney viscosity. JP-A 11-319148 discloses a solid golf ball formed from a rubber composition containing a polybutadiene having a Mooney viscosity of 50 to 69 synthesized with a catalyst of Ni and Co and a polybutadiene having a Mooney viscosity of 20 to 90 synthesized with a catalyst of lanthanoid. JP-A 11-164912 discloses a solid golf ball formed from a rubber composition in which the content of 1,2-vinyl linkage is no more than 2.0% and the ratio of Mw/Mn is no higher than 3.5 (where Mw stands for weight-average molecular weight and Mn stands for number-average molecular weight). JP-A 63-275356 discloses a golf ball formed from a rubber composition incorporated with a polybutadiene having a high Mooney viscosity. JP-A 3-151985 discloses a golf ball formed from a rubber composition containing two kinds of polybutadiene differing in number-average molecular weight. None of these golf balls are satisfactory in rebound resilience.
In addition, JP-A 61-71070 discloses a rubber composition in which two kinds of organic peroxides are used. JP-A 62-112574 discloses a rubber composition in which a small amount of organic peroxide is used. These rubber compositions, however, are deficient in rebound resilience and poor in productivity due to slow vulcanization.
Further additional golf balls are disclosed in JP-A 2001-149505, 2001-149506, 2001-149507, and 2002-293996. However, they have still room for improvement in rebound resilience.